The method will execute the named function, which must be defined
in the given language. There is no assumption made on how various
arguments are passed to the function.

The params argument is a List object
that contains Interpreter.Argument instances,
representing the parameters to be passed to the called
function. An Argument instance is a key-value pair,
where the key is the name of the parameter, and the value is its
desired value. Most languages will ignore the name value and
simply pass to the function, in a positional order, the values of
the argument. Some languages however can pass the arguments in a
different order than the original prototype of the function. For
these languages the ability to associate the actual argument with
a formal parameter using its name is essential.

A particular language implementation may decide to put the
environment, request, response etc. objects in the dynamic scope
available to the function at the time of the call. Other
implementations may decide to pass these as arguments to the
called function.

The current implementation assumes the sitemap implementation
is TreeProcessor.

params - a List value, containing the
parameters to be passed when invoking the continuation. As
opposed to the parameters passed by callFunction,
these parameters will only become available in the language's
environment, if at all.